java.lang.Object | |
↳ | java.io.File |
Known Direct Subclasses |
An abstract representation of file and directory pathnames.
User interfaces and operating systems use system-dependent pathname strings to name files and directories. This class presents an abstract, system-independent view of hierarchical pathnames. An abstract pathname has two components:
"/"
for the UNIX root
directory, or "\\\\"
for a Microsoft Windows UNC pathname, and
The conversion of a pathname string to or from an abstract pathname is
inherently system-dependent. When an abstract pathname is converted into a
pathname string, each name is separated from the next by a single copy of
the default separator character. The default name-separator
character is defined by the system property file.separator
, and
is made available in the public static fields
and separator
of this class.
When a pathname string is converted into an abstract pathname, the names
within it may be separated by the default name-separator character or by any
other name-separator character that is supported by the underlying system.
separatorChar
A pathname, whether abstract or in string form, may be either
absolute or relative. An absolute pathname is complete in
that no other information is required in order to locate the file that it
denotes. A relative pathname, in contrast, must be interpreted in terms of
information taken from some other pathname. By default the classes in the
java.io
package always resolve relative pathnames against the
current user directory. This directory is named by the system property
user.dir
, and is typically the directory in which the Java
virtual machine was invoked.
The parent of an abstract pathname may be obtained by invoking
the getParent()
method of this class and consists of the pathname's
prefix and each name in the pathname's name sequence except for the last.
Each directory's absolute pathname is an ancestor of any File
object with an absolute abstract pathname which begins with the directory's
absolute pathname. For example, the directory denoted by the abstract
pathname "/usr" is an ancestor of the directory denoted by the
pathname "/usr/local/bin".
The prefix concept is used to handle root directories on UNIX platforms, and drive specifiers, root directories and UNC pathnames on Microsoft Windows platforms, as follows:
"/"
. Relative pathnames have no prefix. The abstract pathname
denoting the root directory has the prefix "/"
and an empty
name sequence.
":"
and
possibly followed by "\\"
if the pathname is absolute. The
prefix of a UNC pathname is "\\\\"
; the hostname and the share
name are the first two names in the name sequence. A relative pathname that
does not specify a drive has no prefix.
Instances of this class may or may not denote an actual file-system object such as a file or a directory. If it does denote such an object then that object resides in a partition. A partition is an operating system-specific portion of storage for a file system. A single storage device (e.g. a physical disk-drive, flash memory, CD-ROM) may contain multiple partitions. The object, if any, will reside on the partition named by some ancestor of the absolute form of this pathname.
A file system may implement restrictions to certain operations on the actual file-system object, such as reading, writing, and executing. These restrictions are collectively known as access permissions. The file system may have multiple sets of access permissions on a single object. For example, one set may apply to the object's owner, and another may apply to all other users. The access permissions on an object may cause some methods in this class to fail.
Instances of the File
class are immutable; that is, once
created, the abstract pathname represented by a File
object
will never change.
Fields | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
pathSeparator | The system-dependent path-separator character, represented as a string for convenience. | ||||||||||
pathSeparatorChar | The system-dependent path-separator character. | ||||||||||
separator | The system-dependent default name-separator character, represented as a string for convenience. | ||||||||||
separatorChar | The system-dependent default name-separator character. |
Public Constructors | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Creates a new
File instance by converting the given
pathname string into an abstract pathname. | |||||||||||
Creates a new
File instance from a parent pathname string
and a child pathname string. | |||||||||||
Creates a new
File instance from a parent abstract
pathname and a child pathname string. | |||||||||||
Creates a new File instance by converting the given
file: URI into an abstract pathname.
|
Public Methods | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Tests whether the application can execute the file denoted by this
abstract pathname.
| |||||||||||
Tests whether the application can read the file denoted by this
abstract pathname.
| |||||||||||
Tests whether the application can modify the file denoted by this
abstract pathname.
| |||||||||||
Compares two abstract pathnames lexicographically.
| |||||||||||
Atomically creates a new, empty file named by this abstract pathname if
and only if a file with this name does not yet exist.
| |||||||||||
Creates a new empty file in the specified directory, using the given prefix and suffix strings to generate its name. | |||||||||||
Creates an empty file in the default temporary-file directory, using
the given prefix and suffix to generate its name.
| |||||||||||
Deletes the file or directory denoted by this abstract pathname.
| |||||||||||
Requests that the file or directory denoted by this abstract
pathname be deleted when the virtual machine terminates.
| |||||||||||
Tests this abstract pathname for equality with the given object.
| |||||||||||
Tests whether the file or directory denoted by this abstract pathname
exists.
| |||||||||||
Returns the absolute form of this abstract pathname.
| |||||||||||
Returns the absolute pathname string of this abstract pathname.
| |||||||||||
Returns the canonical form of this abstract pathname.
| |||||||||||
Returns the canonical pathname string of this abstract pathname.
| |||||||||||
Returns the number of unallocated bytes in the partition named by this abstract path name.
| |||||||||||
Returns the name of the file or directory denoted by this abstract
pathname.
| |||||||||||
Returns the pathname string of this abstract pathname's parent, or
null if this pathname does not name a parent directory. | |||||||||||
Returns the abstract pathname of this abstract pathname's parent,
or
null if this pathname does not name a parent
directory. | |||||||||||
Converts this abstract pathname into a pathname string.
| |||||||||||
Returns the size of the partition named by this
abstract pathname.
| |||||||||||
Returns the number of bytes available to this virtual machine on the
partition named by this abstract pathname.
| |||||||||||
Computes a hash code for this abstract pathname.
| |||||||||||
Tests whether this abstract pathname is absolute.
| |||||||||||
Tests whether the file denoted by this abstract pathname is a
directory.
| |||||||||||
Tests whether the file denoted by this abstract pathname is a normal
file.
| |||||||||||
Tests whether the file named by this abstract pathname is a hidden
file.
| |||||||||||
Returns the time that the file denoted by this abstract pathname was
last modified.
| |||||||||||
Returns the length of the file denoted by this abstract pathname.
| |||||||||||
Returns an array of strings naming the files and directories in the
directory denoted by this abstract pathname.
| |||||||||||
Returns an array of strings naming the files and directories in the
directory denoted by this abstract pathname that satisfy the specified
filter.
| |||||||||||
Returns an array of abstract pathnames denoting the files in the
directory denoted by this abstract pathname.
| |||||||||||
Returns an array of abstract pathnames denoting the files and
directories in the directory denoted by this abstract pathname that
satisfy the specified filter.
| |||||||||||
Returns an array of abstract pathnames denoting the files and
directories in the directory denoted by this abstract pathname that
satisfy the specified filter.
| |||||||||||
List the available filesystem roots.
| |||||||||||
Creates the directory named by this abstract pathname.
| |||||||||||
Creates the directory named by this abstract pathname, including any
necessary but nonexistent parent directories.
| |||||||||||
Renames the file denoted by this abstract pathname.
| |||||||||||
A convenience method to set the owner's execute permission for this abstract
pathname.
| |||||||||||
Sets the owner's or everybody's execute permission for this abstract
pathname.
| |||||||||||
Sets the last-modified time of the file or directory named by this
abstract pathname.
| |||||||||||
Marks the file or directory named by this abstract pathname so that
only read operations are allowed.
| |||||||||||
A convenience method to set the owner's read permission for this abstract
pathname.
| |||||||||||
Sets the owner's or everybody's read permission for this abstract
pathname.
| |||||||||||
Sets the owner's or everybody's write permission for this abstract
pathname.
| |||||||||||
A convenience method to set the owner's write permission for this abstract
pathname.
| |||||||||||
Returns the pathname string of this abstract pathname.
| |||||||||||
Constructs a file: URI that represents this abstract pathname.
| |||||||||||
[Expand]
Inherited Methods | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
From class
java.lang.Object
| |||||||||||
From interface
java.lang.Comparable
|
The system-dependent path-separator character, represented as a string
for convenience. This string contains a single character, namely
.
pathSeparatorChar
The system-dependent path-separator character. This field is
initialized to contain the first character of the value of the system
property path.separator
. This character is used to
separate filenames in a sequence of files given as a path list.
On UNIX systems, this character is ':'
; on Microsoft Windows systems it
is ';'
.
The system-dependent default name-separator character, represented as a
string for convenience. This string contains a single character, namely
.
separatorChar
The system-dependent default name-separator character. This field is
initialized to contain the first character of the value of the system
property file.separator
. On UNIX systems the value of this
field is '/'
; on Microsoft Windows systems it is '\\'
.
Creates a new File
instance by converting the given
pathname string into an abstract pathname. If the given string is
the empty string, then the result is the empty abstract pathname.
pathname | A pathname string |
---|
NullPointerException | If the pathname argument is null
|
---|
Creates a new File
instance from a parent pathname string
and a child pathname string.
If parent
is null
then the new
File
instance is created as if by invoking the
single-argument File
constructor on the given
child
pathname string.
Otherwise the parent
pathname string is taken to denote
a directory, and the child
pathname string is taken to
denote either a directory or a file. If the child
pathname
string is absolute then it is converted into a relative pathname in a
system-dependent way. If parent
is the empty string then
the new File
instance is created by converting
child
into an abstract pathname and resolving the result
against a system-dependent default directory. Otherwise each pathname
string is converted into an abstract pathname and the child abstract
pathname is resolved against the parent.
parent | The parent pathname string |
---|---|
child | The child pathname string |
NullPointerException | If child is null
|
---|
Creates a new File
instance from a parent abstract
pathname and a child pathname string.
If parent
is null
then the new
File
instance is created as if by invoking the
single-argument File
constructor on the given
child
pathname string.
Otherwise the parent
abstract pathname is taken to
denote a directory, and the child
pathname string is taken
to denote either a directory or a file. If the child
pathname string is absolute then it is converted into a relative
pathname in a system-dependent way. If parent
is the empty
abstract pathname then the new File
instance is created by
converting child
into an abstract pathname and resolving
the result against a system-dependent default directory. Otherwise each
pathname string is converted into an abstract pathname and the child
abstract pathname is resolved against the parent.
parent | The parent abstract pathname |
---|---|
child | The child pathname string |
NullPointerException | If child is null
|
---|
Creates a new File instance by converting the given file: URI into an abstract pathname.
The exact form of a file: URI is system-dependent, hence the transformation performed by this constructor is also system-dependent.
For a given abstract pathname f it is guaranteed that
new File( f.so long as the original abstract pathname, the URI, and the new abstract pathname are all created in (possibly different invocations of) the same Java virtual machine. This relationship typically does not hold, however, when a file: URI that is created in a virtual machine on one operating system is converted into an abstract pathname in a virtual machine on a different operating system.toURI
()).equals( f.getAbsoluteFile
())
uri | An absolute, hierarchical URI with a scheme equal to "file", a non-empty path component, and undefined authority, query, and fragment components |
---|
NullPointerException | If uri is null |
---|---|
IllegalArgumentException | If the preconditions on the parameter do not hold |
Tests whether the application can execute the file denoted by this abstract pathname.
true
if and only if the abstract pathname exists
and the application is allowed to execute the fileSecurityException | If a security manager exists and its
method denies execute access to the file |
---|
Tests whether the application can read the file denoted by this abstract pathname.
true
if and only if the file specified by this
abstract pathname exists and can be read by the
application; false
otherwiseSecurityException | If a security manager exists and its
method denies read access to the file
|
---|
Tests whether the application can modify the file denoted by this abstract pathname.
true
if and only if the file system actually
contains a file denoted by this abstract pathname and
the application is allowed to write to the file;
false
otherwise.SecurityException | If a security manager exists and its
method denies write access to the file
|
---|
Compares two abstract pathnames lexicographically. The ordering defined by this method depends upon the underlying system. On UNIX systems, alphabetic case is significant in comparing pathnames; on Microsoft Windows systems it is not.
pathname | The abstract pathname to be compared to this abstract pathname |
---|
Atomically creates a new, empty file named by this abstract pathname if and only if a file with this name does not yet exist. The check for the existence of the file and the creation of the file if it does not exist are a single operation that is atomic with respect to all other filesystem activities that might affect the file.
Note: this method should not be used for file-locking, as
the resulting protocol cannot be made to work reliably. The
FileLock
facility should be used instead.
true
if the named file does not exist and was
successfully created; false
if the named file
already existsIOException | If an I/O error occurred |
---|---|
SecurityException | If a security manager exists and its
method denies write access to the file |
Creates a new empty file in the specified directory, using the given prefix and suffix strings to generate its name. If this method returns successfully then it is guaranteed that:
deleteOnExit()
method.
The prefix
argument must be at least three characters
long. It is recommended that the prefix be a short, meaningful string
such as "hjb"
or "mail"
. The
suffix
argument may be null
, in which case the
suffix ".tmp"
will be used.
To create the new file, the prefix and the suffix may first be
adjusted to fit the limitations of the underlying platform. If the
prefix is too long then it will be truncated, but its first three
characters will always be preserved. If the suffix is too long then it
too will be truncated, but if it begins with a period character
('.'
) then the period and the first three characters
following it will always be preserved. Once these adjustments have been
made the name of the new file will be generated by concatenating the
prefix, five or more internally-generated characters, and the suffix.
If the directory
argument is null
then the
system-dependent default temporary-file directory will be used. The
default temporary-file directory is specified by the system property
java.io.tmpdir
. On UNIX systems the default value of this
property is typically "/tmp"
or "/var/tmp"
; on
Microsoft Windows systems it is typically "C:\\WINNT\\TEMP"
. A different
value may be given to this system property when the Java virtual machine
is invoked, but programmatic changes to this property are not guaranteed
to have any effect upon the temporary directory used by this method.
prefix | The prefix string to be used in generating the file's name; must be at least three characters long |
---|---|
suffix | The suffix string to be used in generating the file's
name; may be null , in which case the
suffix ".tmp" will be used |
directory | The directory in which the file is to be created, or
null if the default temporary-file
directory is to be used |
IllegalArgumentException | If the prefix argument contains fewer than three
characters |
---|---|
IOException | If a file could not be created |
SecurityException | If a security manager exists and its
method does not allow a file to be created |
Creates an empty file in the default temporary-file directory, using
the given prefix and suffix to generate its name. Invoking this method
is equivalent to invoking
.createTempFile(prefix, suffix, null)
prefix | The prefix string to be used in generating the file's name; must be at least three characters long |
---|---|
suffix | The suffix string to be used in generating the file's
name; may be null , in which case the
suffix ".tmp" will be used |
IllegalArgumentException | If the prefix argument contains fewer than three
characters |
---|---|
IOException | If a file could not be created |
SecurityException | If a security manager exists and its
method does not allow a file to be created |
Deletes the file or directory denoted by this abstract pathname. If this pathname denotes a directory, then the directory must be empty in order to be deleted.
true
if and only if the file or directory is
successfully deleted; false
otherwiseSecurityException | If a security manager exists and its method denies
delete access to the file
|
---|
Requests that the file or directory denoted by this abstract pathname be deleted when the virtual machine terminates. Files (or directories) are deleted in the reverse order that they are registered. Invoking this method to delete a file or directory that is already registered for deletion has no effect. Deletion will be attempted only for normal termination of the virtual machine, as defined by the Java Language Specification.
Once deletion has been requested, it is not possible to cancel the request. This method should therefore be used with care.
Note: this method should not be used for file-locking, as
the resulting protocol cannot be made to work reliably. The
FileLock
facility should be used instead.
SecurityException | If a security manager exists and its method denies
delete access to the file |
---|
Tests this abstract pathname for equality with the given object.
Returns true
if and only if the argument is not
null
and is an abstract pathname that denotes the same file
or directory as this abstract pathname. Whether or not two abstract
pathnames are equal depends upon the underlying system. On UNIX
systems, alphabetic case is significant in comparing pathnames; on Microsoft Windows
systems it is not.
obj | The object to be compared with this abstract pathname |
---|
true
if and only if the objects are the same;
false
otherwise
Tests whether the file or directory denoted by this abstract pathname exists.
true
if and only if the file or directory denoted
by this abstract pathname exists; false
otherwiseSecurityException | If a security manager exists and its
method denies read access to the file or directory
|
---|
Returns the absolute form of this abstract pathname. Equivalent to
new File(this.
.getAbsolutePath()
)
SecurityException | If a required system property value cannot be accessed. |
---|
Returns the absolute pathname string of this abstract pathname.
If this abstract pathname is already absolute, then the pathname
string is simply returned as if by the
method. If this abstract pathname is the empty abstract pathname then
the pathname string of the current user directory, which is named by the
system property getPath()
user.dir
, is returned. Otherwise this
pathname is resolved in a system-dependent way. On UNIX systems, a
relative pathname is made absolute by resolving it against the current
user directory. On Microsoft Windows systems, a relative pathname is made absolute
by resolving it against the current directory of the drive named by the
pathname, if any; if not, it is resolved against the current user
directory.
SecurityException | If a required system property value cannot be accessed. |
---|
Returns the canonical form of this abstract pathname. Equivalent to
new File(this.
.getCanonicalPath()
)
IOException | If an I/O error occurs, which is possible because the construction of the canonical pathname may require filesystem queries |
---|---|
SecurityException | If a required system property value cannot be accessed, or
if a security manager exists and its method denies
read access to the file |
Returns the canonical pathname string of this abstract pathname.
A canonical pathname is both absolute and unique. The precise
definition of canonical form is system-dependent. This method first
converts this pathname to absolute form if necessary, as if by invoking the
getAbsolutePath()
method, and then maps it to its unique form in a
system-dependent way. This typically involves removing redundant names
such as "." and ".." from the pathname, resolving
symbolic links (on UNIX platforms), and converting drive letters to a
standard case (on Microsoft Windows platforms).
Every pathname that denotes an existing file or directory has a unique canonical form. Every pathname that denotes a nonexistent file or directory also has a unique canonical form. The canonical form of the pathname of a nonexistent file or directory may be different from the canonical form of the same pathname after the file or directory is created. Similarly, the canonical form of the pathname of an existing file or directory may be different from the canonical form of the same pathname after the file or directory is deleted.
IOException | If an I/O error occurs, which is possible because the construction of the canonical pathname may require filesystem queries |
---|---|
SecurityException | If a required system property value cannot be accessed, or
if a security manager exists and its method denies
read access to the file |
Returns the number of unallocated bytes in the partition named by this abstract path name.
The returned number of unallocated bytes is a hint, but not a guarantee, that it is possible to use most or any of these bytes. The number of unallocated bytes is most likely to be accurate immediately after this call. It is likely to be made inaccurate by any external I/O operations including those made on the system outside of this virtual machine. This method makes no guarantee that write operations to this file system will succeed.
getTotalSpace()
.SecurityException | If a security manager has been installed and it denies
RuntimePermission ("getFileSystemAttributes")
or its checkRead(String) method denies
read access to the file named by this abstract pathname |
---|
Returns the name of the file or directory denoted by this abstract pathname. This is just the last name in the pathname's name sequence. If the pathname's name sequence is empty, then the empty string is returned.
Returns the pathname string of this abstract pathname's parent, or
null
if this pathname does not name a parent directory.
The parent of an abstract pathname consists of the pathname's prefix, if any, and each name in the pathname's name sequence except for the last. If the name sequence is empty then the pathname does not name a parent directory.
null
if this pathname
does not name a parent
Returns the abstract pathname of this abstract pathname's parent,
or null
if this pathname does not name a parent
directory.
The parent of an abstract pathname consists of the pathname's prefix, if any, and each name in the pathname's name sequence except for the last. If the name sequence is empty then the pathname does not name a parent directory.
null
if this pathname
does not name a parentConverts this abstract pathname into a pathname string. The resulting
string uses the default name-separator character
to
separate the names in the name sequence.
Returns the size of the partition named by this abstract pathname.
SecurityException | If a security manager has been installed and it denies
RuntimePermission ("getFileSystemAttributes")
or its checkRead(String) method denies
read access to the file named by this abstract pathname |
---|
Returns the number of bytes available to this virtual machine on the
partition named by this abstract pathname. When
possible, this method checks for write permissions and other operating
system restrictions and will therefore usually provide a more accurate
estimate of how much new data can actually be written than getFreeSpace()
.
The returned number of available bytes is a hint, but not a guarantee, that it is possible to use most or any of these bytes. The number of unallocated bytes is most likely to be accurate immediately after this call. It is likely to be made inaccurate by any external I/O operations including those made on the system outside of this virtual machine. This method makes no guarantee that write operations to this file system will succeed.
getFreeSpace()
.SecurityException | If a security manager has been installed and it denies
RuntimePermission ("getFileSystemAttributes")
or its checkRead(String) method denies
read access to the file named by this abstract pathname |
---|
Computes a hash code for this abstract pathname. Because equality of
abstract pathnames is inherently system-dependent, so is the computation
of their hash codes. On UNIX systems, the hash code of an abstract
pathname is equal to the exclusive or of the hash code
of its pathname string and the decimal value
1234321
. On Microsoft Windows systems, the hash
code is equal to the exclusive or of the hash code of
its pathname string converted to lower case and the decimal
value 1234321
. Locale is not taken into account on
lowercasing the pathname string.
Tests whether this abstract pathname is absolute. The definition of
absolute pathname is system dependent. On UNIX systems, a pathname is
absolute if its prefix is "/"
. On Microsoft Windows systems, a
pathname is absolute if its prefix is a drive specifier followed by
"\\"
, or if its prefix is "\\\\"
.
true
if this abstract pathname is absolute,
false
otherwise
Tests whether the file denoted by this abstract pathname is a directory.
true
if and only if the file denoted by this
abstract pathname exists and is a directory;
false
otherwiseSecurityException | If a security manager exists and its
method denies read access to the file
|
---|
Tests whether the file denoted by this abstract pathname is a normal file. A file is normal if it is not a directory and, in addition, satisfies other system-dependent criteria. Any non-directory file created by a Java application is guaranteed to be a normal file.
true
if and only if the file denoted by this
abstract pathname exists and is a normal file;
false
otherwiseSecurityException | If a security manager exists and its
method denies read access to the file
|
---|
Tests whether the file named by this abstract pathname is a hidden
file. The exact definition of hidden is system-dependent. On
UNIX systems, a file is considered to be hidden if its name begins with
a period character ('.'
). On Microsoft Windows systems, a file is
considered to be hidden if it has been marked as such in the filesystem.
true
if and only if the file denoted by this
abstract pathname is hidden according to the conventions of the
underlying platformSecurityException | If a security manager exists and its
method denies read access to the file |
---|
Returns the time that the file denoted by this abstract pathname was last modified.
long
value representing the time the file was
last modified, measured in milliseconds since the epoch
(00:00:00 GMT, January 1, 1970), or 0L
if the
file does not exist or if an I/O error occursSecurityException | If a security manager exists and its
method denies read access to the file
|
---|
Returns the length of the file denoted by this abstract pathname. The return value is unspecified if this pathname denotes a directory.
0L
if the file does not exist. Some
operating systems may return 0L
for pathnames
denoting system-dependent entities such as devices or pipes.SecurityException | If a security manager exists and its
method denies read access to the file
|
---|
Returns an array of strings naming the files and directories in the directory denoted by this abstract pathname.
If this abstract pathname does not denote a directory, then this
method returns null
. Otherwise an array of strings is
returned, one for each file or directory in the directory. Names
denoting the directory itself and the directory's parent directory are
not included in the result. Each string is a file name rather than a
complete path.
There is no guarantee that the name strings in the resulting array will appear in any specific order; they are not, in particular, guaranteed to appear in alphabetical order.
null
if
this abstract pathname does not denote a directory, or if an
I/O error occurs.SecurityException | If a security manager exists and its checkRead(String) method denies read access to
the directory
|
---|
Returns an array of strings naming the files and directories in the
directory denoted by this abstract pathname that satisfy the specified
filter. The behavior of this method is the same as that of the
list()
method, except that the strings in the returned array
must satisfy the filter. If the given filter
is null
then all names are accepted. Otherwise, a name satisfies the filter if
and only if the value true
results when the FilenameFilter.accept(File, String)
method
of the filter is invoked on this abstract pathname and the name of a
file or directory in the directory that it denotes.
filter | A filename filter |
---|
filter
. The array will be empty if the
directory is empty or if no names were accepted by the filter.
Returns null
if this abstract pathname does not denote
a directory, or if an I/O error occurs.SecurityException | If a security manager exists and its checkRead(String) method denies read access to
the directory
|
---|
Returns an array of abstract pathnames denoting the files in the directory denoted by this abstract pathname.
If this abstract pathname does not denote a directory, then this
method returns null
. Otherwise an array of File
objects
is returned, one for each file or directory in the directory. Pathnames
denoting the directory itself and the directory's parent directory are
not included in the result. Each resulting abstract pathname is
constructed from this abstract pathname using the File(File, String)
constructor. Therefore if this
pathname is absolute then each resulting pathname is absolute; if this
pathname is relative then each resulting pathname will be relative to
the same directory.
There is no guarantee that the name strings in the resulting array will appear in any specific order; they are not, in particular, guaranteed to appear in alphabetical order.
null
if this abstract pathname does not denote a
directory, or if an I/O error occurs.SecurityException | If a security manager exists and its checkRead(String) method denies read access to
the directory |
---|
Returns an array of abstract pathnames denoting the files and
directories in the directory denoted by this abstract pathname that
satisfy the specified filter. The behavior of this method is the same
as that of the listFiles()
method, except that the pathnames in
the returned array must satisfy the filter. If the given filter
is null
then all pathnames are accepted. Otherwise, a pathname
satisfies the filter if and only if the value true
results when
the FilenameFilter.accept(File, String)
method of the filter is
invoked on this abstract pathname and the name of a file or directory in
the directory that it denotes.
filter | A filename filter |
---|
null
if this abstract pathname does not denote a
directory, or if an I/O error occurs.SecurityException | If a security manager exists and its checkRead(String) method denies read access to
the directory |
---|
Returns an array of abstract pathnames denoting the files and
directories in the directory denoted by this abstract pathname that
satisfy the specified filter. The behavior of this method is the same
as that of the listFiles()
method, except that the pathnames in
the returned array must satisfy the filter. If the given filter
is null
then all pathnames are accepted. Otherwise, a pathname
satisfies the filter if and only if the value true
results when
the FileFilter.accept(File)
method of the
filter is invoked on the pathname.
filter | A file filter |
---|
null
if this abstract pathname does not denote a
directory, or if an I/O error occurs.SecurityException | If a security manager exists and its checkRead(String) method denies read access to
the directory |
---|
List the available filesystem roots.
A particular Java platform may support zero or more
hierarchically-organized file systems. Each file system has a
root
directory from which all other files in that file system
can be reached. Windows platforms, for example, have a root directory
for each active drive; UNIX platforms have a single root directory,
namely "/"
. The set of available filesystem roots is affected
by various system-level operations such as the insertion or ejection of
removable media and the disconnecting or unmounting of physical or
virtual disk drives.
This method returns an array of File
objects that denote the
root directories of the available filesystem roots. It is guaranteed
that the canonical pathname of any file physically present on the local
machine will begin with one of the roots returned by this method.
The canonical pathname of a file that resides on some other machine
and is accessed via a remote-filesystem protocol such as SMB or NFS may
or may not begin with one of the roots returned by this method. If the
pathname of a remote file is syntactically indistinguishable from the
pathname of a local file then it will begin with one of the roots
returned by this method. Thus, for example, File
objects
denoting the root directories of the mapped network drives of a Windows
platform will be returned by this method, while File
objects
containing UNC pathnames will not be returned by this method.
Unlike most methods in this class, this method does not throw
security exceptions. If a security manager exists and its checkRead(String)
method denies read access to a
particular root directory, then that directory will not appear in the
result.
File
objects denoting the available
filesystem roots, or null
if the set of roots could not
be determined. The array will be empty if there are no
filesystem roots.Creates the directory named by this abstract pathname.
true
if and only if the directory was
created; false
otherwiseSecurityException | If a security manager exists and its
method does not permit the named directory to be created
|
---|
Creates the directory named by this abstract pathname, including any necessary but nonexistent parent directories. Note that if this operation fails it may have succeeded in creating some of the necessary parent directories.
true
if and only if the directory was created,
along with all necessary parent directories; false
otherwiseSecurityException | If a security manager exists and its
method does not permit verification of the existence of the
named directory and all necessary parent directories; or if
the
method does not permit the named directory and all necessary
parent directories to be created
|
---|
Renames the file denoted by this abstract pathname.
Many aspects of the behavior of this method are inherently platform-dependent: The rename operation might not be able to move a file from one filesystem to another, it might not be atomic, and it might not succeed if a file with the destination abstract pathname already exists. The return value should always be checked to make sure that the rename operation was successful.
dest | The new abstract pathname for the named file |
---|
true
if and only if the renaming succeeded;
false
otherwiseSecurityException | If a security manager exists and its
method denies write access to either the old or new pathnames |
---|---|
NullPointerException | If parameter dest is null
|
A convenience method to set the owner's execute permission for this abstract pathname.
An invocation of this method of the form file.setExcutable(arg) behaves in exactly the same way as the invocation
file.setExecutable(arg, true)
executable | If true , sets the access permission to allow execute
operations; if false to disallow execute operations |
---|
true
if and only if the operation succeeded. The
operation will fail if the user does not have permission to
change the access permissions of this abstract pathname. If
executable
is false
and the underlying
file system does not implement an excute permission, then the
operation will fail.SecurityException | If a security manager exists and its
method denies write access to the file |
---|
Sets the owner's or everybody's execute permission for this abstract pathname.
executable | If true , sets the access permission to allow execute
operations; if false to disallow execute operations |
---|---|
ownerOnly | If true , the execute permission applies only to the
owner's execute permission; otherwise, it applies to everybody.
If the underlying file system can not distinguish the owner's
execute permission from that of others, then the permission will
apply to everybody, regardless of this value. |
true
if and only if the operation succeeded. The
operation will fail if the user does not have permission to
change the access permissions of this abstract pathname. If
executable
is false
and the underlying
file system does not implement an execute permission, then the
operation will fail.SecurityException | If a security manager exists and its
method denies write access to the file |
---|
Sets the last-modified time of the file or directory named by this abstract pathname.
All platforms support file-modification times to the nearest second,
but some provide more precision. The argument will be truncated to fit
the supported precision. If the operation succeeds and no intervening
operations on the file take place, then the next invocation of the
method will return the (possibly
truncated) lastModified()
time
argument that was passed to this method.
time | The new last-modified time, measured in milliseconds since the epoch (00:00:00 GMT, January 1, 1970) |
---|
true
if and only if the operation succeeded;
false
otherwiseIllegalArgumentException | If the argument is negative |
---|---|
SecurityException | If a security manager exists and its
method denies write access to the named file |
Marks the file or directory named by this abstract pathname so that only read operations are allowed. After invoking this method the file or directory is guaranteed not to change until it is either deleted or marked to allow write access. Whether or not a read-only file or directory may be deleted depends upon the underlying system.
true
if and only if the operation succeeded;
false
otherwiseSecurityException | If a security manager exists and its
method denies write access to the named file |
---|
A convenience method to set the owner's read permission for this abstract pathname.
An invocation of this method of the form file.setReadable(arg) behaves in exactly the same way as the invocation
file.setReadable(arg, true)
readable | If true , sets the access permission to allow read
operations; if false to disallow read operations |
---|
true
if and only if the operation succeeded. The
operation will fail if the user does not have permission to
change the access permissions of this abstract pathname. If
readable
is false
and the underlying
file system does not implement a read permission, then the
operation will fail.SecurityException | If a security manager exists and its
method denies write access to the file |
---|
Sets the owner's or everybody's read permission for this abstract pathname.
readable | If true , sets the access permission to allow read
operations; if false to disallow read operations |
---|---|
ownerOnly | If true , the read permission applies only to the
owner's read permission; otherwise, it applies to everybody. If
the underlying file system can not distinguish the owner's read
permission from that of others, then the permission will apply to
everybody, regardless of this value. |
true
if and only if the operation succeeded. The
operation will fail if the user does not have permission to
change the access permissions of this abstract pathname. If
readable
is false
and the underlying
file system does not implement a read permission, then the
operation will fail.SecurityException | If a security manager exists and its
method denies write access to the file |
---|
Sets the owner's or everybody's write permission for this abstract pathname.
writable | If true , sets the access permission to allow write
operations; if false to disallow write operations |
---|---|
ownerOnly | If true , the write permission applies only to the
owner's write permission; otherwise, it applies to everybody. If
the underlying file system can not distinguish the owner's write
permission from that of others, then the permission will apply to
everybody, regardless of this value. |
true
if and only if the operation succeeded. The
operation will fail if the user does not have permission to change
the access permissions of this abstract pathname.SecurityException | If a security manager exists and its
method denies write access to the named file |
---|
A convenience method to set the owner's write permission for this abstract pathname.
An invocation of this method of the form file.setWritable(arg) behaves in exactly the same way as the invocation
file.setWritable(arg, true)
writable | If true , sets the access permission to allow write
operations; if false to disallow write operations |
---|
true
if and only if the operation succeeded. The
operation will fail if the user does not have permission to
change the access permissions of this abstract pathname.SecurityException | If a security manager exists and its
method denies write access to the file |
---|
Returns the pathname string of this abstract pathname. This is just the
string returned by the
method.getPath()
Constructs a file: URI that represents this abstract pathname.
The exact form of the URI is system-dependent. If it can be determined that the file denoted by this abstract pathname is a directory, then the resulting URI will end with a slash.
For a given abstract pathname f, it is guaranteed that
newso long as the original abstract pathname, the URI, and the new abstract pathname are all created in (possibly different invocations of) the same Java virtual machine. Due to the system-dependent nature of abstract pathnames, however, this relationship typically does not hold when a file: URI that is created in a virtual machine on one operating system is converted into an abstract pathname in a virtual machine on a different operating system.File
( f.toURI()).equals( f.getAbsoluteFile
())
SecurityException | If a required system property value cannot be accessed. |
---|
This method is deprecated.
This method does not automatically escape characters that
are illegal in URLs. It is recommended that new code convert an
abstract pathname into a URL by first converting it into a URI, via the
toURI
method, and then converting the URI into a URL
via the URI.toURL
method.
Converts this abstract pathname into a file:
URL. The
exact form of the URL is system-dependent. If it can be determined that
the file denoted by this abstract pathname is a directory, then the
resulting URL will end with a slash.
MalformedURLException | If the path cannot be parsed as a URL |
---|